Evrim Yazgin
Cosmos science journalist
An analysis of more than 500 fossils from central Europe’s Polish Basin has shown how dinosaurs became the dominant lifeforms on land by the beginning of the Jurassic period.
The fossils, however, are not bones, teeth or even footprints. They’re bromalites – the fossilised remains of digestive material such as faeces or vomit. To be specific, the bromalites include coprolites (fossil poo), cololites (fossil faecal material preserved in the gut of an animal) and regurgitalites (fossil remains that have been regurgitated by an animal).
The analysis of the Polish Basic bromalites is published in Nature.
3D imaging revealed the contents of the ancient, digested food. This was compared to other evidence in the fossil record including climate and plant data.
It showed that omnivorous early dinosaurs were able to outcompete the non-dinosaur land animals that had dominated before. These early dinosaurs evolved into carnivores and herbivores toward the end of the Triassic period.
Dinosaurs first evolved around the middle of the Triassic, about 240 million years ago.
“However, terrestrial ecosystems dominated by dinosaurs … did not appear until the Early Jurassic, some 30 million years later,” the authors write.
The authors suggest their findings point to substantial changes in vegetation, likely caused by increased volcanic activity, which spurred on the evolution of early dinosaur ancestors. This would lead to larger and more diverse herbivores and, as a result, larger carnivores.
“We suggest that the processes shown by the Polish data may explain global patterns, shedding new light on the environmentally governed emergence of dinosaur dominance and gigantism that endured until the end-Cretaceous mass extinction,” the authors add.
